Does climate therapy at moderate altitudes improve pulmonary function in asthma patients? A systematic review

Allergic bronchial asthma is one of the most common chronic diseases worldwide. For many years, the climate at moderate altitude has been used as an alternative therapy for patients suffering from bronchial asthma. The aim of such therapy is to reduce the medication dose and to improve the quality of life for each patient. The aim of our current work was to assess published data evaluating the effects of climate therapy at moderate altitude on the health status of patients with bronchial asthma. The health status is represented through surrogate parameters for the pulmonary function (forced expiratory volume in one second (FEV1)), bronchial hyperresponsiveness (PC20), and inflammation (total number of eosinophils, eosinophilic cationic protein, and exhaled nitric oxide).

Our systematic review included randomized controlled trials (RCTs) and single-armed studies with adults and children participating. Included in our review were climate therapies occurring at moderate altitudes between 1,500 and 2,500 m and evaluation of patient FEV1 or PC20 values.

A literature research in MEDLINE and EMBASE identified three RCTs, two clinically controlled trials, and 15 single-armed studies. Analysis revealed a lack of evidence regarding the moderate altitude therapy arising from small sample sizes, deficits in documentation, and heterogeneous results. Most of the studies, however, showed a tendency for improvement of the analyzed parameters.

The currently available data do not allow for valid and generalizable recommendations with respect to moderate altitude therapy for patients with allergic bronchial asthma. There is a need for additional, qualitatively strong research including larger sample sizes and randomized, controlled trial design.